It is a known fact that certain unwanted amounts of foreign components in other materials, namely metallic materials, have negative consequences on the physical and chemical properties of these materials. Thus it is undesirable, that a metal or a metallic alloy contains certain amounts of other metals. An example is the unacceptable lead content in a copper alloy, which are used for water-bearing components in sanitary facilities.
The complex problem mentioned above is important notably for gaseous impurities, because the corresponding atoms are in different materials, namely metallic materials, soluble in comparably high concentrations and on the other hand in many cases highly mobile in these materials. Such gaseous impurities often affect materials properties in an undesirable way.
Among the gaseous impurities special emphasis has to be placed on hydrogen. Its severe negative effect on materials, especially metallic materials, is known for some time by the term hydrogen embrittlement. Especially in steels, and parts or work pieces made out of steel, a considerable impairment of performance has to be expected.
Especially for steels the unwanted absorption of hydrogen occurs during its production, as well as during its finishing and during its application. As examples the processes of casting, welding, bating and galvanizing are mentioned (Hoffmann, F.: Linkewitz, T.; Mayr P.: Wasserstoffversprödung—Meinungen und Fakten. In: Einsatzhärtung. Berichtsband der AWT-ATTT-Tagung, 29.-30. April 1998, Aachen, Arbeitsgemeinschaft Wärmebehandlung und Werkstofftechnik e.V. (AWT)/Association) Technique de Traitment Thermique (ATTT), Wiebaden (1998) S. 259-267; Hoffmann, F.: Linkewitz, T.; Mayr P.: Wasserstoffaufnahme beim Einsatzhärten. HTM 54 (1999) 10-12).
In addition, the incorporation of hydrogen in heat treated steel components, namely from the gas phase during carbonization, is especially high (Wyss, U.: Aufkohlen in Gasen. In: Benninghoff, H. (Hrsg.); Wärmebehandlung der Bau-und Werkzeugstähle. BAZ Verlag, Basel/1978). By this process hydrogen is generated during the primary decomposition reaction of carbonizing reactants forming the gaseous atmosphere and via surface reactions leading to the formation of carbon. Also, during the so-called direct hardening, a concentration of 2.2 weight ppm (ppm by weight) hydrogen (which corresponds to 122.1 atomic ppm) can be attained. (Streng, H.; Grosch, J.; Razim, C.: Wasserstoffaufnahme und-abgabe beim Einsatzhärten. HTM (Härterei-Technische Mitteilungen) 42 (1987) 245-260). Because of the high mobility of hydrogen atoms within the iron lattice of the steel hydrogen is distributed over the entire volume of the material during usual carbonizing times. Therefore, the typical “fish eyes” at inclusions occur also within internal regions of thick components.
In addition, hydrogen may also form and enter materials during corrosion of metallic alloys in hydrogen containing media. Thus hydrogen is entering from the surface into the steel component during the service of lubricated engine parts via tribochemical reactions.
The features of hydrogen embrittlement and the preceding events in the material are studied and discussed for a long time. An attempt was made to explain the damage caused by hydrogen with for principal mechanisms (Neumann, P.; Grundlagen der Wirkung von Waserstoff auf die Rissbildung in Stälen. Stahl and Eisen 107 (1987) 577-583). These four mechanisms are:                Formation of crack tips at brittle carbides due to the three axial stress state.        Internal formation of methane by hydrogen reacting with dissolved carbon (internal decarburization).        Direct mechanical damage by high hydrogen equilibrium pressures (recombination of the dissolved hydrogen atoms to hydrogen molecules, especially at defects).        Decrease of the cohesion forces by hydrogen accompanied by a disposition to brittle fracture.        
For gaseous impurities, especially for the described hydrogen embrittlement, it is not only problematic that embrittlement occurs but also that the effect of these gaseous impurities cannot be detected with sufficient sensitivity. Basically it is possible in the case of hydrogen to detect it quantitatively. Though for quantitative determinations, which are indispensable for a fundamental understanding of the underlying processes, no sufficiently sensitive techniques are available, or the available techniques are not or not sufficiently applicable in the environment of the fabrication or operation of the corresponding materials.
Especially a quantitative determination is also for the state of the art known U.S. Pat. No. 3,732,076 not conceivable. There the determination of hydrogen is conducted via microscopic or electron microscopic observation. Based on the resulting inaccurate data of the used samples a reproducible quantitative determination of hydrogen concentrations is not possible.
In this context it is known from the publication of R. Kirchheim, Acta Metallurgica, Vol. 27, Issue 5, pp. 869 to 878 (1979), that the diffusion coefficient of oxygen in copper, niobium and tantalum can be determined with the aid of metals in which oxygen has a higher solubility. In this nearly 30 years old publication neither the set of problems associated with gaseous impurities nor their detection is mentioned. The issue of hydrogen embrittlement is not addressed as well.
Accordingly the present invention concerns the detection of high sensitivity impurities, namely gaseous impurities, in materials, especially in metallic materials. Thereby a quantitative determination of these impurities may become possible. On the other hand the present invention also has the goal to provide a method by which materials, especially metallic materials, are protected against gaseous impurities or their concentration is reduced. Namely the negative effect of hydrogen shall be diminished or eliminated.